The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 2003
Filed:
May. 08, 2001
John R Moffatt, Corvallis, OR (US);
Joseph W Tsang, Corvallis, OR (US);
Hewlett-Packard Development Company, L.P., Houston, TX (US);
Abstract
A method for dispersing a pigment in an aqueous solution is provided. The method comprises: (a) providing the pigment, which is distinguished in having an azo group and either a &bgr;-diketo structure or a hydroxyl group, each conjugatively associated with the azo group; (b) treating a surface of the pigment with a base having sufficient strength (e.g., a pK of at least 6) to generate a negative charge on the pigment; and (c) reacting the negatively charged pigment with either (1) a first hydrophilic molecule containing at least one functional group comprising a carbon—carbon double bond and a carbonyl that is alpha to the carbon—carbon double bond which reacts via addition to form a hydrophilic group on the pigment or (2) a second hydrophilic molecule containing at least one functional group selected from the group consisting of anionic functional groups, cationic functional groups, and zwitterionic functional groups and at least one suitable leaving group which reacts via substitution to form a hydrophilic group on the pigment. The treated pigment is rendered comparatively soluble in water-based inks, thereby eliminating the need for any dispersant to disperse the pigment.